Analyze the Graph: Finding Where f(x) > 0

Graph Analysis with Sign Determination

Find all values of x x

wheref(x)>0 f\left(x\right) > 0 .

XXXYYY-4-4-4

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Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Find all values of x x

wheref(x)>0 f\left(x\right) > 0 .

XXXYYY-4-4-4

2

Step-by-step solution

In this problem, we are tasked with determining the values of x x for which the function f(x) f(x) is positive. We have been provided a graphical representation of the function, and we will use this graph to find our solution.

1. Restate the problem: We need to find all values of x x where the function f(x) f(x) is greater than zero, based on its graphical representation. 2. Identify key information: The graph is typically that of some function f(x) f(x) . The graph shows points and lines that illustrate where the function is above and below the x-axis. Points or curves on or above the x-axis indicate positive values. 3. Potential approach: Analyze where the graph is above the x-axis. 5. The most appropriate approach is to visually inspect the graph to identify when the curve is above the x-axis. 6. Steps needed: - Identify any turning points or intersections with the x-axis. - Determine the segments of the x-axis where the function is above it. 8. Simplify the inspection by focusing on intervals separated by intersections with the x-axis. 9. Consider that the function might only touch the x-axis at specific points, like at roots, and analyze behavior around these points.

Based on the graph, we observe the following behavior of the function f(x) f(x) :

  • The function intersects the x-axis at x=4 x = -4 . This indicates a potential root or turning point where the function transitions from positive to negative or vice versa.
  • From the graph, it appears that the function is above the x-axis on both sides of x=4 x = -4 , except exactly at x=4 x = -4 , where it touches the x-axis.

Hence, the function f(x) f(x) is positive for x>4 x > -4 and for x<4 x < -4 . Note that exactly at x=4 x = -4 , the function is zero, not positive.

Therefore, the solution is: x>4 x > -4 or x<4 x < -4 .

In conclusion, the function f(x) f(x) is positive for these values of x x , except the point where it touches the x-axis.

The corresponding choice given the problem's options is:

x>4 x > -4 or x<4 x < -4

3

Final Answer

x>4 x > -4 or x<4 x < -4

Key Points to Remember

Essential concepts to master this topic
  • Visual Rule: Function is positive when graph lies above x-axis
  • Technique: Check intervals separated by x-intercept at x=4 x = -4
  • Check: Test points: left of -4 gives positive, right of -4 gives positive ✓

Common Mistakes

Avoid these frequent errors
  • Including the x-intercept in the solution
    Don't include x = -4 in your answer when finding where f(x) > 0! At x = -4, the function equals zero, not greater than zero. Always exclude points where the graph touches or crosses the x-axis when finding positive regions.

Practice Quiz

Test your knowledge with interactive questions

The graph of the function below intersects the X-axis at points A and B.

The vertex of the parabola is marked at point C.

Find all values of \( x \) where \( f\left(x\right) > 0 \).

AAABBBCCCX

FAQ

Everything you need to know about this question

Why isn't x = -4 included if the graph touches the x-axis there?

+

Great observation! At x=4 x = -4 , the function equals zero, not a positive value. We need f(x)>0 f(x) > 0 , which means strictly greater than zero.

How do I know the function is positive on both sides of x = -4?

+

Look at the graph carefully! The curve is above the x-axis for all x-values except exactly at x=4 x = -4 where it just touches the axis. Above the x-axis means positive values.

What's the difference between f(x) > 0 and f(x) ≥ 0?

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f(x)>0 f(x) > 0 means strictly positive (excludes zero), while f(x)0 f(x) ≥ 0 means non-negative (includes zero). For this problem, we exclude x=4 x = -4 because we want strictly positive.

Can I write the answer as x ≠ -4 instead?

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Not quite! While x4 x ≠ -4 excludes the right point, it doesn't specify that we want all other real numbers. The correct notation is x<4 x < -4 or x>4 x > -4 .

How can I verify this answer makes sense?

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Pick test points! Try x=5 x = -5 (left of -4) and x=0 x = 0 (right of -4). If the graph shows positive y-values at these points, your answer is correct!

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